1. Field of the Art
This invention relates to an endoscopic insertion instrument for medical use, and more particularly to a jet nozzle to be connected to a wash fluid feed passage for washing an observation window on a distal end face of the insertion instrument.
2. Prior Art
Illustrated in FIG. 8 is a typical endoscope in general use in medical fields. In that figure, indicated at 1 is a manipulating head assembly, at 2 an insertion instrument, and at 3 a universal cable. Along with an illumination window or windows, an observation window 4 is provided on a rigid tip end section 2a of the insertion instrument 2. An optical objective lens system is disposed on the inner side of the observation window 4, and an image sensor device such as a solid-state image sensor or the like is located at the focus of the optical objective lens system. Fitted in the observation window 4 is a cover glass which also functions as a foremost lens element of the objective lens system. When the endoscopic insertion instrument 2 is introduced into a body cavity of a patient, it is very likely for the surface of the foremost lens element to be smeared by deposition of body fluids or other contaminants. Deposition of such contaminants on the lens surface results in restrictions of the view field and therefore in insufficient examination of an intracavitary portion under observation.
Thus, a device for washing an endoscopic observation window is necessary for washing the exterior surface of the observation window and removing contaminants therefrom whenever a view through the observation window 4 is smeared by deposition of contaminants during examination of a body cavity. For washing the observation window 4, wash water is spurted toward the lens surface under a predetermined pressure to wash away contaminants, and then compressed air is blasted on the lens surface to purge water droplets.
For these purposes, the observation window washing device is equipped with an air pump 5 and a water tank 6. A compressed air pipe 7 from the air pump 5 is connected to the universal cable 3. Further, a tank pressurizing air pipe 8 is branched off the compressed air pipe 7, and connected to the water tank 6 which receives a supply of water through a wash water feed pipe 9. In this instance, the tank pressurizing air pipe 8 is opened above the surface of water in the tank 6, while the wash water feed pipe 9 is opened under the water surface, preferably in the vicinity of the bottom of the water tank 6. Compressed air pipe 7 and the water pipe 9 are extended into the manipulating head assembly 1 by way of the universal cable 3 and connected to a air/water feed valve 10 which is provided on the manipulating head assembly 1.
Connected from the air/water feed valve 10 are an air feed pipe 11 and a water feed pipe 12, which are jointed together in a fore end portion of the insertion instrument 2 into an air/water junction pipe 13. The air/water junction pipe 13 is communicated with a fluid passage 14 which is bored in the rigid tip end section 2a. The fluid passage 14 is opened in a distal end face of the rigid tip end section 2a, and provided with a spout nozzle 15 at its open end. A wash fluid, consisting of water and compressed air flowing through the fluid passage 14, is turned and spurted toward the observation window 4 by the spout nozzle 15 under a predetermined pressure. Therefore, the spout nozzle 15 is provided with a mouth end which is turned toward the observation window 4.
The air/water feed valve 10 can be manipulated by a finger of a hand which grips the manipulating head assembly 1. Normally, communication between the wash water pipe 9 and the water feed pipe 12 is blocked, while the compressed air pipe 7 is connected to the air feed pipe 11 and at same time communicated with the atmosphere through an atmospheric passage (not shown) which is provided in the air/water feed valve 10. Thus, at this time, the air/water feed is in a suspended state. Since the compressed air pipe 7 is in communication with the atmosphere, the pump 5 is substantially in an unloaded state. As soon as the atmospheric passage is blocked by a finger or the like, the air pump 5 turns into a loaded state and starts to compress air. Resulting compressed air is supplied to the jet nozzle 15 from the compressed air pipe 7 through the air feed pipe 11 and the compressed air pipe 8. At the same time, the air pressure is led into the wash water tank 6 through the compressed air pipe 8 to pressurize the wash water tank 6. However, no wash water is supplied to the jet nozzle 15 because the communication between the wash water pipe 9 and the water feed pipe 12 is still blocked by the air/water feed valve 10.
Upon pushing in the air/water feed valve 10 from the position shown in the drawing, communication between the compressed air pipe 7 and the air feed pipe 11 is blocked while communication between the wash water pipe 9 and the water feed pipe 12 is opened. Further, compressed air from the air pump 5 is introduced into the wash water tank 6 through the tank pressurizing pipe 8 to pressurize the wash water tank 8, whereupon wash water is supplied to the fluid passage 14 under a predetermined pressure through the wash water pipe 9 and the water feed pipe 12. As a result, wash water is spurted toward the observation window 4 from the jet nozzle 15.
As shown in FIG. 9, the prior art jet nozzle 15 is constituted, for example, by a tubular body portion 15a, and a jet spout passage portion 15b which is turned approximately through 90 degrees from the tubular body portion 15a and terminated with an injecting nozzle hole 15c at its fore distal end. In this instance, the jet spout passage portion 15b is a flat passage. The passage of the jet spout passage portion can be formed simply by bending an intermediate portion of the tubular body portion 15a through 90 degrees in a flattened shape. However, in the case of the particular example shown, a lower side portion of the jet spout passage portion 15 is removed to spurt a fluid toward the surface of the rigid tip end section 2a. 
A wash fluid including wash water and/or compressed air, which is spurted out through the nozzle hole 15c of the jet nozzle 15, should be precisely directed toward and distributed over the entire surfaces of the observation window 4. In addition, a wall portion of the jet nozzle 15 should not block a view field through the observation window 4. In order to fulfill these requirements, the nozzle hole 15c needs to be located at a certain distance from the observation window 4. Accordingly, position of the jet nozzle 15 and direction of the jet spout passage portion 15b on the rigid tip end section 2a of the insertion instrument 2 are determined depending upon the position of the observation window 4 itself. Besides, the jet nozzle 15 is also restricted by the position of an illumination window or windows. In a case where the jet nozzle 15 is located in the proximity of an illumination window, it is likely that illumination light is reflected off the jet nozzle and directed toward the observation window 4 as harmful light to endoscopic observation images. Therefore, the jet nozzle 15 should be located at a distance from an illumination window. Of course, the position of an illumination window is determined depending upon the position of the observation window 4. Namely, in order to distribute illumination light uniformly over the entire view field which is obtained through the observation window 4, illumination windows need to be located in positions on the right and left sides and in the proximity of the observation window 4.
The position of the observation window 4 on the rigid tip end section 2a of the insertion instrument 2 is limited by relations with its view field. More specifically, normally the proximal end of the rigid tip end section 2a is connected to an angle section which is flexibly and angularly bent in an upward, downward, rightward or leftward direction to turn the rigid tip end section 2a into a desired direction. Therefore, the bending direction and the position of the observation window 4 are in certain relations with each other. The observation window 4 is located either in a center position or in an off-center position on the distal end face of the rigid tip end section 2a. In case the observation window 4 is located in an off-center position, an operator can manipulate and control the insertion instrument more easily if the observation window 4 is located in an upper position in the bending direction of the angle section. Further, the position of an outlet opening of a biopsy channel, which is provided in the insertion instrument 2 for passing forceps or other biopsy or surgical instruments, is also closely related with the position of the observation window 4. Namely, as a biopsy instrument is protruded into a body cavity from the outlet opening of the biopsy channel, it should always be within the view field of the observation window 4. Besides, the an extension of the outlet opening of the biopsy channel should not intersect a direction of fluid injection by the jet nozzle 15. In short, once the observation window 4 is located in a certain position on the rigid tip end section 2a of the insertion instrument 2, the positions of the illumination windows, outlet opening of the biopsy channel and jet nozzle 15 are determined accordingly.
After setting the jet nozzle 15 in a position which satisfies the conditions as discussed above, the position of the fluid passage 14 in the rigid tip end section 2a is determined accordingly. The fluid passage 14 is connected to the air/water junction pipe 13 in the flexible angle section which is connected to the proximal end of rigid tip end section 2a. The air/water junction pipe 13 in the angle section has to be constituted by a soft, flexible tube with a wall thickness which is sufficient to ensure immunity from buckling even when the insertion instrument 2 is bent into angular forms. For this purpose, the junction pipe 13 which is extended from the rigid tip end section 2a has to be relatively large in outside diameter. In addition, a lead portion of the junction pipe 13 has to be located in such a way as to avoid interference with various component parts such as light guide, signal cable and biopsy channel which are are fitted in or threaded through the angle section of the insertion instrument 2, on the proximal side of the rigid tip end section 2a. 
Further, in a case where the optical objective lens system is arranged to move part of its lens components in the direction of optical axis for a zooming action, for example, it is necessary to incorporate a mechanism for axially displacing a movable lens or lenses by remote control. In this regard, it has been the general practice to move movable lenses by mean of a control cable having tightly closed rotation transmission coils sheathed in a flexible sleeve. The junction pipe should be located in such a position which would not interfere with a control cable when the latter is fitted into the insertion instrument 2. Thus, the provision of a control cable, in addition to the above described various internally fitted component parts which are interdependent on each other in positional layout, necessarily results in a conspicuous increase in diameter of the endoscopic insertion instrument 2.
With the foregoing situations in view, it is an object of the present invention to reduce the diameter of an endoscopic insertion instrument by minimizing dead spaces in the insertion instrument in connecting a fluid passage to a rigid tip end section of the insertion instrument.
It is another object of the present invention to provide a jet nozzle which spurts jets of a wash fluid toward an observation window of an endoscopic insertion instrument, which give a greater freedom in locating a wash fluid passage in a fore end portion of the insertion instrument, allowing to lay out other internally fitted component parts of the insertion instrument in a rational way.
It is still another object of the present invention to provide a jet nozzle of the sort as mentioned above, which can suppress increases in diameter of an endoscopic insertion instrument to a minimum by making it possible to locate a wash fluid passage in a suitable position, particularly in a case where a control cable is additionally fitted into the insertion instrument for the purpose of driving a movable lens or lenses of an optical objective lens system.
In accordance with the present invention, for achieving the above-stated objectives, there is provided a jet nozzle to be connected to a distal end of a wash fluid passage in a narrow and elongated endoscopic insertion instrument for spurting a wash fluid toward and on an observation window of an optical image pickup system fitted in a rigid tip end section of the insertion instrument. The jet nozzle according to the present invention is characterized by the provision of: a wash fluid inlet passage provided at a proximal end of the jet nozzle coaxially in communication with an axial wash fluid passage in the rigid tip end section of the insertion instrument; a jet spout passage portion located on a distal end face of the rigid tip end section and terminating with a jet spout opening of a predetermined width, the jet spout passage portion being provided with a straight flow rectifying passage of a predetermined length to the jet outlet opening; and a turn passage connected between the wash fluid inlet passage and the jet spout passage portion to turn a flow passage of the wash fluid in a radially diverting direction from the axial wash fluid passage and connected to the jet spout passage portion in a radially diverted position on the distal end face of the rigid tip end section.
In this instance, the flow rectifying passage of the jet spout passage portion of the jet nozzle is in the form of either a straight passage or a forwardly diverging passage having a predetermined width. The turn passage of the jet nozzle is bent in a curved shape to switch the flow direction of the wash fluid and connected to the flow rectifying passage in a radially diverted position from the axial wash fluid passage. In a case where part of lenses of the optical objective lens system are movable lenses, a lens drive means such as a control cable having tightly wound coils sheathed in a flexible sleeve is fitted into the insertion instrument to permit to move the movable lenses in the direction of optical axis by remote control. Preferably, the flow rectifying passage of the jet nozzle is located on the distal end face of the rigid tip end section at a position which is on an axial extension line from the lens drive means, while the turn passage is connected to the axial wash fluid passage which is located in an evasive position with respect to the lens drive means.
The above and other objects, features and advantages of the present invention will become apparent from the following particular description of the invention, taken in conjunction with the accompanying drawings which show by way of example preferred embodiments of the invention. Needless to say, the present invention should not be construed as being limited to particular forms shown in the drawings.